Retained size computation is incorrect

[pyricau]

Context: https://androiddev.social/@py/113176281321505098

Repro:

  @Test fun `Updating first dominator through longer path after already updated to common ancestor denominator removes retained size`() {
    hprofFile.dump {
      val answer = string("42")
      val life = "com.example.Life" instance { field["answer"] = answer }
      val universe = "com.example.Universe" instance { field["answer"] = answer }
      val everything = "com.example.Everything" watchedInstance {
        field["life"] = life
        field["universe"] = universe
      }
      val fiber = "com.example.Fiber" instance { field["life"] = life }
      val towel = "com.example.Towel" instance { field["fiber"] = fiber }
      "Hitchhiker" clazz {
        staticField["guide"] = everything
        staticField["practicalTool"] = towel
      }
    }

    val everythingInstanceLeak = retainedInstances().single().leakTraces.first()
    // Only "Universe" is dominated by "Everything", the watched instance.
    // shallow size for "everything" is 2 refs (life + universe) => 8 bytes
    // Universe has one ref: 4 bytes => 8 + 4 = 12.
    // Instead we get 24 because the incorrect algorithm is including the answer string
    // which is 4 bytes for int size, 2 bytes per char => 12 bytes
    assertThat(everythingInstanceLeak.retainedObjectCount).isEqualTo(2)
  }